Of this abstraction. The values for getRadius() or getCircumference() in the above mentioned example may very well be stored straight, or they could be calculated, it would not subject to your caller; the setters might or may not have side effects; it isn't going to subject for the caller. 近年来这方面的研究开发主要是围绕结构 https://affordablehousingprojectsinbhiwadi.blogspot.com